WPG, Lux, Lumens, blah. Who really knows what they all mean, how to apply them properly to our tanks, and most of all, what our plants require? I think you'd be hard pressed to find many, if anyone, that does. So, let's look at some simple, general, factors.
You have a large tank that's 2' deep. That tells me you'll need either enough low intensity lighting to reach the bottom, or some intense lighting that will reach the bottom, usually achieved by good reflectors or point-source lighting (HQI). You are striking me as someone who simply wants a nice, simple planted tank to enjoy, and is not demanding of perfect aquascaping.
Let me ask you this: Are you or are you not dedicated to CO2 use? There is no half-assing here. It really is black or white. This will make a substantial difference in your lighting needs. Either way, you can acheive your desires, so don't let that decision influence you.
I prefer CO2. So let's start there (I will try to balance CO2/non-CO2 so that either way you go you will have good results). You are using 40w lights w/ no reflectors that are positioned high above the tank. While this can sustain plants, it probably won't grow them very well. I don't know your exact set-up, but if it's DIY, I would replace 2 of your 5 bulbs with T5HO's with good reflectors. So, you would have 3-40w NO bulbs to burn all day, with 2 T5's to run for about 6 hours per day on a timer. This sounds pretty good. You get to mix intensity with extended viewing pleasure. With non-CO2, you simply cut the photoperiod down--cutting the T5's down to 4 hours would probably do it. T5HO retro kits (or just parts) are very cheap. As for any algae woes, that would merit another thread.